principles of anatomy and...

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Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

CHAPTER 23The Respiratory System

Principles of Anatomy and Physiology

14th Edition

The purpose of the chapter is to:1. Describe the anatomy of the respiratory

system

2. Understand the physiology of the respiratory system

3. Describe the events that cause inhalation, exhalation, and gas exchange

4. Learn how oxygen and carbon dioxide are transported in the blood

Introduction


� Respiration is the exchange of gases between the atmosphere, blood, and cells

� The combination of 3 processes is required for respiration to occur� Ventilation (breathing)

� External (pulmonary) respiration

� Internal (tissue) respiration

� The cardiovascular system assists the respiratory system by transporting gases

Breathing and Respiration


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Pulmonary Ventilation


� Pulmonary Ventilation

Interactions Animation:

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Structurally, the components of the respiratory system are divided into 2 parts:

1. Upper respiratory system

2. Lower respiratory system

Functionally, the components of the respiratory system are divided into 2 zones:

1. Conducting zone

2. Respiratory zone

Structures of the Respiratory System


Respiratory System Anatomy


� The Respiratory System

Anatomy Overview:


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Respiratory System Tissues


� Respiratory System Tissues


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Anatomy Overview:

Structures of the Respiratory System


� The upper respiratory system consists of the nose, pharynx, and associated structures

� The lower respiratory system consists of the larynx, trachea, bronchi, and lungs

Respiratory System Anatomy


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Overview: Nose, Pharynx, Larynx, and Trachea


The external portion of the nose is made of cartilage and skin and is lined with mucous membrane

Cartilaginous Framework of the Nose


The bony framework of the nose is formed by the frontal, nasal, and maxillary bones

Internal Anatomy of the Nose


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Nasal Conchae and Meatuses


1. Root

2. Apex

3. Bridge4. External naris

Surface Anatomy of the Nose


The pharynx functions as a passageway for air and food, provides a resonating chamber for speech sounds, and houses the tonsils, which participate in immunological reactions against foreign invaders

Pharynx


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The larynx (voice box) is a passageway that connects the pharynx and trachea

Larynx


The larynx contains vocal folds, which produce sound when they vibrate

Larynx


Structures of Voice Production


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The trachea extends from the larynx to the primary bronchi

Trachea


At the superior border of the 5th thoracic vertebrae, the trachea branches into a right primary bronchus which enters the right lung and a left primary bronchus which enters the left lung

Bronchi


Upon entering the lungs, the primary bronchi further divide to form smaller and smaller diameter branches

� The terminal bronchioles are the end of the conducting zone

Bronchi


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The lungs are paired organs in the thoracic cavity

Lungs


The lungs are enclosed and protected by the pleural membrane

Lungs


Lobes and Fissures of the Lungs


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� When the conducting zone ends at the terminal bronchioles, the respiratory zone begins

� The respiratory zone terminates at the alveoli, the “air sacs” found within the lungs

Alveoli


Alveoli are sac-like structures

Alveoli in a Lobule of a Lung


There are 2 kinds of alveolar cells, Type I and Type II

Alveolus


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The respiratory membrane is composed of: 1. A layer of type I and type II alveolar cells and

associated alveolar macrophages that constitutes the alveolar wall

2. An epithelial basement membrane underlying the alveolar wall

3. A capillary basement membrane that is often fused to the epithelial basement membrane

4. The capillary endothelium

Respiratory Membrane


� Blood enters the lungs via the pulmonary arteries (pulmonary circulation) and the bronchial arteries (systemic circulation)

� Blood exits the lungs via the pulmonary veins and the bronchial veins

� Ventilation-perfusion coupling� Vasoconstriction in response to hypoxia diverts

blood from poorly ventilated areas to well ventilated areas

Blood Supply to the Lungs



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In pulmonary ventilation, air flows between the atmosphere and the alveoli of the lungs because of alternating pressure differences created by contraction and relaxation of respiratory muscles

� Inhalation

� Exhalation

Pulmonary Ventilation


Pressure changes that drive inhalation and exhalation are governed, in part, by Boyle’s Law

� The volume of a gas varies inversely with its pressure

Boyle’s Law


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Muscles of Inhalation and Exhalation


Position of the Diaphragm During Inhalation and Exhalation


Pressure Changes in Pulmonary Ventilation


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Surface tension� Inwardly directed force in the alveoli which must

be overcome to expand the lungs during each inspiration

Elastic recoil� Decreases the size of the alveoli during expiration

Compliance� Ease with which the lungs and thoracic wall can

be expanded

Other Factors Affecting Pulmonary Ventilation


� Eupnea� Apnea

� Dyspnea

� Tachypnea

� Costal breathing

� Diaphragmatic breathing

Breathing Patterns and Respiratory Movements



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Lung Volumes and Capacities


Lung Volumes and Capacities


� Respiratory Volumes and Capacities

Anatomy Overview:


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Dalton’s law� Each gas in a mixture of gases exerts its own

pressure as if no other gases were present

Henry’s law� The quantity of a gas that will dissolve in a liquid

is proportional to the partial pressure of the gas and its solubility coefficient when the temperature remains constant

Exchange of Oxygen and Carbon Dioxide


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During external respiration, oxygen will diffuse from the alveoli into the pulmonary capillaries

� CO2 moves in the opposite direction

During internal respiration, oxygen will diffuse from the systemic capillaries into the tissue

� CO2 moves in the opposite direction

External and Internal Respiration


Gas Exchange


� Gas Exchange



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Oxygen:� 1.5% of the O2 is dissolved in the plasma

� 98.5% of the O2 is carried by hemoglobin (Hb)

Carbon dioxide:� 7% of the CO2 is dissolved in the plasma

� 23% of the CO2 is carried by Hb inside red blood cells as carbaminohemoglobin

� 70% of the CO2 is transported as bicarbonate ions (HCO3)

Transport of O2 and CO2 in the Blood


Transport of Oxygen and Carbon Dioxide


� Gas Transport



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� PO2

� pH

� Temperature

� BPG

� Type of Hb

Factors Affecting the Affinity of Hbfor O2


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Control of Respiration


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Cortical influences� Allow conscious control of respiration that may be

needed to avoid inhaling noxious gases or water

Chemoreceptor � Central and peripheral chemoreceptors monitor

levels of O2 and CO2 and provide input to the respiratory center



Regulation of Ventilation


� Regulation of Ventilation



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Structures That Control Respiration


� Structures That Control Respiration

Anatomy Overview:


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Hypercapnia� A slight increase in PCO2 (and thus H+)

� Stimulates central chemoreceptors

Hypoxia� Oxygen deficiency at the tissue level

� Caused by a low PO2 in arterial blood due to high altitude, airway obstruction or fluid in the lungs



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Regulation of Blood pH


� Role of the Respiratory System in pH Regulation



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The respiratory and cardiovascular systems make adjustments in response to both the intensity and duration of exercise

� As cardiac output rises, the blood flow to the lungs, termed pulmonary perfusion, increases as well

� The O2 diffusing capacity may increase threefold during maximal exercise so there is a greater surface area available for O2 diffusion

Exercise and the Respiratory System


Development of the Respiratory System


Aging results in decreased:� Vital capacity

� Blood O2 level

� Alveolar macrophage activity

� Ciliary action of respiratory epithelia

Consequently, elderly people are more susceptible to pneumonia, bronchitis, emphysema, and other issues

Aging and the Respiratory System


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Disorders: Homeostatic Imbalances

� Asthma

� Chronic obstructive pulmonary disease

� Lung cancer

� Pneumonia

� Tuberculosis

� Common cold

� Pulmonary edema

� Cystic fibrosis

� Asbestos-related diseases

� Sudden infant death syndrome

� Acute respiratory distress


Copyright 2014 John Wiley & Sons, Inc. All rights reserved. Reproduction or translation of this work beyond that permitted in section 117 of the 1976 United States Copyright Act without express permission of the copyright owner is unlawful. Request for further information should be addressed to the Permission Department, John Wiley & Sons, Inc. The purchaser may make back-up copies for his/her own use only and not for distribution or resale. The Publisher assumes no responsibility for errors, omissions, or damages caused by the use of these programs or from the use of the information herein.

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